Process of producing smoke clouds from moving aircraft



- 1 619 183 March 1 3927' D. B. BRADNER ET AL PROCESS OF PRODUCING SMOKECLOUDS FROM MOVING AIRCRAFT Filed May 8, 1925 fililmdner INVENTORS- andAgZ ChQZcZJ E. Qglebyby A TTORNE Y.

Patented Mar. 1, 1927.

UNITED STATES 1,619,183 PATENT OFFICE.

DONALD B. BRADNEB AND NICHOLAS E. OGLESBY, 0F EDGEWOOD, MARYLAND.

PROCESS OF PRODUCING SMOKE CLOUDS FROM MOVING AIRCRAFT.

Application filed May 8, 1925. Serial No. 28,981.

velocity and has more specific application to the sprinkling .ofsmoke-producing liquids from aircraft, such as aeroplanes, dirigibles,etc.

Among the objects of this invention is the provision of a processwhereby smokeproducing liquids may be dropped from aircraft, wherein theliquid reacts with one or more of the constituents of the air oratmosphere and generates a smoke screen as it falls. This is animprovement over the present means of generating smoke screens whereinthe smoke material is dropped to the ground in containers or else is setout on the ground, and wherein the success of the operation of producingthe screen is dependent on the rise of a smoke cloud.

A further object of this invention is the provision of a process whichmay be employed for laying screens of smoke from aeroplanes to protectthe planes from antiaircra'ft attack or to protect land fortifications,troops, or ships from enemy fire.

A still further object of this invention is the provision of a processfor producing long and extensive fronts of smoke in an economic, safeand rapid manner.

Other, further and more specific objects of the invention will becomereadily ap-parent to persons skilled in the art from a consideration ofthe following description when taken in conjunction with theaccompanying drawing.

When a liquid is dropped from an elevation at rest with respect to theair it will fall to the ground in the form of stable drops. If, however,the liquid be dropped from a body moving at high velocity, the liquidwill immediately upon release become broken up intoa mist and all of theliquid or a considerable portion thereof will be dispersed in the airand not reach the ground. By ejecting the liquid under pressure from anaeorplane or other moving aircraft so that the liquid leaves the planeat approximately the same velocity as the plane passes through the airbut in a substantially opposite direction, the liquid will fall as ifpoured from an elevation at rest, and travels to the ground insubstantially stable drops. The present invention makes use of thismethod of ejecting smoke-producing liquids from moving aircraft.

"from the tank (1) to the gauge This invention is not limited to anyclass of smoke-producing liquids and may also be applied to solutions ofsolids in liquids. The success and effectiveness of the smoke screenislargely dependent on the chemical and physical properties of theliquid'employed. We prefer to cm )loy a smoke-producing liquid such as'liill, SnOh, oleum and chlorsulphonic acid. We may, however, use othermixtures or solutions, for example a solution of sulphur t-rioxide inchlorsulphonic acid. These smoke-producing materials are not stable inthe air but react with one or more constituents of the air to formsubstantially stable products.

hen these smoke-producing liquids are ejected under pressure from anaeroplane or other moving aircraft so that the liquid leaves the planeat approximately the same velocity as the plane passes through the airbut in a substantially opposite direction, the liquid falls in the formof relatively stable drops and reacts with the constituents of the airto form a smoke screen. The effect produced is the generation of afalling smoke curtain, which reaches the ground in the form of a long,high screen. Dependent on the height at which the plane is travellingwhen the liquid is released, the smoke curtain may be made tohang in theair, or may be made to rest on the ground.

Reference is to be had to the accompanying drawings wherein we haveillustrated, more or less diagrammatically, =an apparatus which issuitable for carryingout our invention. Fig. 1 is a side elevation of anaeroplane equipped with the special apparatus for carrying out ourinvention. Fig. 2 is a detail view illustrating diagrammatically theparts of the apparatus.

The apparatus comprises a tank (1) for holding the liquid to besprinkled. A pressure cylinder (2) containing compressed carbon dioxideor other suitable gas is connected to the tank (1) by the conduit (3)and the branching conduits l) and (5). The conduit (6) connects with theconduit (5) and terminates at the back of the aeroplane in a nozzle (7).The tank (1) is fastened to the aeroplane b the straps 01' bands (8),and the cylinder 2) and the conduits.

are held in position by any suitable means.

The tank (1) is provided with a pressure gauge (9), and when handlingcorrosive substances provide a trap (10) in the line (11) (9) The as anair release outlet.

. be sprinkled. In the conduit cated near the conduit (6) 1s a valve(17) gauge side of the trap (10) contains a su1table non-corrodingmaterial, such as chlorinated parafiin oils, while the other side of thetrap contains mercury. The gauge (9) is positioned convenient to theoperator.

Compressed gas is supplied from the cylinder (2) thru the cylinder valve(12), conduit (3), valve (13) and conduit (4) to the tank (1) containingthe l1qu1d to be sprm kled. The liquid is forced from the tank (1 by thecompressed gas thru the conduit (5;, valve (14), conduit (6) and thenozzle (7) at the rear of the aeroplane.

The conduit (4) is also provided with a valve (15), which serves as anemergency pressure release outlet, and when the tank (1) is being filledthis valve (15) serves The conduit (5) is provided with a valve (16 nearthetank (1), this valve being used 1n the ord nary filling of the tank(1) with the liquid to I I 3) and lowhieh serves in an emergency forpermitting the escape of pressure should a forced landing be necessary.

The tank (1) may be filled wlth the liquid to be sprinkled in anyconvenient manner. For example, air is allowed to escape by opening thevalve (15) and the liquid is forced into the tank (1) through the valve(16), the valve (14) being closed during the operation. When the tank(1) has been filled the valves (15) and (16) are agaln closed. a

In operating this device for sprinkling the liquid, it is advisable 'notto introduce pressure into the system until the lane has left theground. All the valveselng closed, valve (13) is opened and then valve(12) is opened gradually. Pressure immediately builds up in the systemas shown b the gauge (9). Ordinarily, it is desirable to start with aninitial pressure of 225 pounds per square inch in order that thepressure he maintained at the .desired point while valve (14) is beingopened and until attention can again be given to the pressure control.Valve (14) should be opened gradually in order to prevent a water hammereffect which might result in a broken connection. If decrease inpressure takes place at this point, valve (12) is again opened andmanipulated so as to maintain the gauge pressure at about 170 lbs. persq. in. This pressure will discharge approximately 300 pounds of liquidover a peripd of 20 seconds and of a distance of one half mile. Afterthe tank has been completely discharged a rapid decrease in pressurewill be noted.

1 Ordinarily, it is advisable to allow the gas,

for example carbon dioxide,

This invention is applicable to various types of aeroplanes andaircraft, and the .to be sprinkled may to exhaust itself in order toclear all the conduits and lines.

amount of liquid which may be carried varies with the carrying capacityof the particular aircraft.

Although in this specific illustration we employ compressed carbondioxide as the source of gas pressure, it is to be understood that ourinvention is not limited in this respect but that other gases which donot have undesirable chemical action on the. liquid be employed, andthat mechanical apparatus, for example a pump or air compressor, may beemployed in lieu of the compressed carbon dioxide. Also, othersmoke-producing liquids than those named herein may be employed withoutdcparting from the spirit of this invention.

In describing the operation of our device, a gas pressure of 175 lbs.per square in. of the liquid is given. This figure represents a valuebased uponthe physical and chemical constants of the liquids sprinkled,the average speed of the plane, the size of the nozzle and theresistance of the conduits and fittings. By controlling the pressure ofthe gas in the tank containing the liquid to be sprinkled, the velocityof ejection may be made approximately equal to the velocity of the planethrough the air at any given time.

In the velocity of the wind with reference to the ground is ofsubstantially no importance, the vital consideration being the velocityof the moving aircraft in the air which is the factor resulting in thebreaking up of the drops of liquid into smaller particles. By projectingthe liquid from the moving ai1'- craft with a velocity substantiallyequal and opposite to the velocity in the air of the moving aircraft,counter-longitudinal motion between the liquid and the air at the timeof release of the liquid is prevented and the result is that the liquidfalls as if poured from an elevation at rest, and travels to the groundin substantially stable drops. When the liquid is a smoke-producingmaterial, which reacts with oneor'more constituents of "the air to formsubstantially stable. visible roducts, the effect produced is that of afa ling smoke curtain.

In the following claims, wherever refer-' ence is made to the velocityof the moving body, aircraft-or airplane, it is intended to refer to thevelocity in the air and not the speed relative to the ground.

The present invention is not limited to the specific details set forthin the foregoing examples which should be construed as illustrative andnot by way of limitation, and

which may be eflected therein without departing from the spirit andscope of this invention, it is desired that only such limitations beimposed as are indicated in the appended claims.

practice of our invention, the actual 1n view of the numerousmodifications We claim as our invention:

1. In a process of producing a smoke screen, ejecting from a moving bodya liquid which reacts with a constituent of the air to produce a smoke,said body moving at a velocity sufiicient to produce a highly dispersiveaction upon a liquid falling therefrom and said smoke-producing liquidbeing ejected in a direction substantially opposite to that of themoving body and at a velocity to counteract said dispersive action.

2. In a process of producing a falling curtain of smoke, ejecting from amoving body a liquid which reacts with a constituent of the air toproduce a smoke, said bod moving at a velocity sufficient to pro uce ahighly dispersive action upon a liquid falling therefrom and saidsmoke-producing liquid being ejected in a direction substantiallyopposite to that of the moving body and at a velocity suiiicient tocounteract substantially all of said dispersive action.

3. In a process of producing a curtain of smoke, ejecting from a movingbody a liquid which reacts with a constituent of the air to produce asmoke, said body moving at a velocity sufiicient to produce a highlydispersive action upon a liquid falling therefrom and said liquid beingejected in the form of a spray, at a velocity substantially equal and ina direction substantially opposite to that of the moving body.

' 4. In a process of producing a smoke screen, ejecting from anaeroplane while flying a liquid which reacts with a. constituent of theair to produce a smoke, said liquid being ejected in a directionsubstantially opposite to that of the moving aeroplane and thedifi'erence in velocity between the aeroplane and the liquid ejectedtherefrom not exceeding 20 miles per hour.

5. In a process of producing a falling curtain of smoke, ejecting frommoving aircraft a liquid which reacts with a constituent of the air toproduce a smoke, said aircraft moving at a velocity sutiicient toproduce a highly dispersive action upon a liquid falling therefrom andsaid smoke-producing liquid being ejected in the form of a spray, in adirection substantially opposite to that of the moving aircraft and at avelocity suflicientto counteract the greater portion of said dispersiveaction.

6. In a process of producing a smoke screen, ejecting from a movingaeroplane a liquid which reacts with a constituent of the air to producea smoke, said aeroplane moving at a velocity sufficient to produce ahighly despersive action upon a liquid falling therefrom, and saidsmoke-producing liquid being ejected at the rear of and backward to themotion of said aeroplane and at a velocity closely approaching that ofthe moving aeroplane.

7. In a process of producing a smoke screen, ejecting from a moving bodyliquid Tic/1 said body moving at a velocity sufficient to produce ahighly dispersive action upon a liquid falling therefrom and said TiClbeing ejected in a direction substantially opposite to that of themoving body and at a velocity to count ract said dispersive action.

8. In a process of producing a falling curtain of smoke, ejecting frommoving aircraft liquid TiCh, said aircraft moving at a velocitysufiicient to produce a highly dispersive action upon a liquid fallingtherefrom and said TiCl being ejected in the form of a spray, in adirection substantially opposite to that of the moving aircraft and at avelocity sufficient to counteract the greater portion of said dispersiveaction.

DONALD E. BRADNER. NICHOLAS E. OGLESBY.

